The tributary load is the load carried by any one post in your deck. The live load is the weight of everything placed on the deck – furnishings, plants, people, etc. Another rule of thumb is to layout fixtures in odd numbers (3, 5, 7, etc. Joists at 12”o.c. The joists are usually not visible, so using expensive premium timbers isn’t necessary as long as the beam structure is properly placed. What they do tell you is the maximum length of a beam for a particular joist span. It also permits the use of 2x8s at 16”o.c. Attached decks require a ledger for securing it to the building, while free-standing ones need an additional beam and post framework. The free end of the joist often either rests on the beam or cantilevers over it. Joist Span – Non-Ledger Deck. A single spruce 2×6 may span 8’-8”o.c, and a double spruce 2×6 joist reaches 25% further, or 10’-10”. We recommend this joist span calculator, which has the following functions: Deck joist span tables commonly identify the maximum span for different wood types and joist spacing. Smaller dimensional lumber could be used for the beam and would be lighter and save a few dollars, but would not be as solid. The deck surface is commonly one 7” step down from building entrances or at the same level as inside floors. Many composite decking brands and all 5/4” wood boards are limited to 12”o.c. There are three ways to determine deck joist span and spacing – formula, calculator, and joist sizing and span tables. Decks may provide access to various rooms of a building and also to the ground which affects the design and height of the deck. and 16”o.c. It requires two 3” or 3-1/2” fasteners in every joist and is also spaced 1/8” to 3/8” apart. You are limited to two-ply beams – that means two pieces of lumber, such as two 2x8s nailed together for use as a deck support beam. and 16”o.c., although some manufactured board brands are designed for the 24”o.c. On the flipside, a post will touch the deck every time it’s used, providing a steady support system. *Values from Table R507.6 of the 2018 IRC. Lower grades, economy, or utility lumber have too many knots or large knots that weaken the lumber too much for structural use. Regardless of the span, 2×6 joists are usually limited to ground-level decks without railings. Determining the proper deck joist sizing and spacing occurs at the planning stage. Most 2” thick wood planks are fine traversing joist spacing of 12”o.c., 16”o.c. I hope you’ve found it helpful and are now confident enough to plan and space your deck support posts! Most decks have joists that are attached to a ledger board, which is affixed to the house. Check out our table below which is based on the information on Table R507.5 of the 2018 IRC. The future is … Therefore, a longer deck span means that you’ll have to space your deck support posts closer together. If you are unable to attach or don’t want to attach, your deck joists to your house with a ledger board, then your design becomes more flexible. As mentioned above, code will also inform you how high you are allowed to build a deck using 4×4 support posts, which is usually never above 5’ from the footing to the deck surface. Use calcium chloride or rock salt to melt the snow and ice from the deck surface. All are common methods and may affect the overall design and cost of the project. Deck joist spacing affects how well supported the deck boards are; if too far apart, the decking will be springy or soft, and can sag. But the 2015 IRC included a new one (Table R507.5) that will make it easy for deck builders to spec a joist size for a given span and joist spacing. joist spacing increases material cost between $70 for 2x8s and $100 for 2x10s. ), and the height off the ground. Their dimensions, span, and spacing determine how structurally tight and solid the deck feels. The benefit of using 4x4s is that you can put them on a smaller diameter deck footing, which thus requires less concrete and digging. If upgrading the size of the lumber for your deck beam means using one less footing, then it might be worth the extra cost as you would save time and effort avoiding digging the third footing. Maximum joist span of a 2X8 is 10’ – 6” at 16” o.c. can span 9’-11” but that drops to 6’-8” with a cantilever. If your deck is more than 2’ high, your corner support posts will need to be braced parallel and perpendicular to the support beam and deck joists, respectively. with a live load rating of 40psf will span 9’-9” while a 2×12 yellow pine at 16”o.c. A shorter beam span means more deck support posts. BEAM SIZE & ASSEMBLY REQUIREMENTS Deck beam spans shall be in accordance with Table 3 and can extend past the post face up to L B /4 as shown in Figure 3. Attaching your deck to your house negates the need for a beam – and posts – near your home. An improperly supported deck can result in collapse – there’s a reason deck codes exist and you don’t want to invite thirty people over to a barbecue to find out that your deck can’t support that many people. The longer your deck beam, the more deck support posts you’ll need when building a deck. Figure 2. Choose Material and the Size for Your Joists, Example: How Far Apart to Place Deck Joists for 12 x 12 Deck, SPF #2 Grade Joist Configurations for 12–foot deck. A larger beam can span a greater distance, requiring fewer but larger footings. The more elaborate the deck design, the greater the need for the input of a Structural Engineer. Additionally, the beam support structure, type of deck board desired, the pattern for installing the decking, and of course, the Building Code must be factored into the decision too. REMEMBER THESE THINGS. Eugene has been a DIY enthusiast for most of his life and loves being creative while inspiring creativity in others. The 2018 IRC is a good place to start as is your local Code which may adjust values or loads for regional conditions. The distance between deck support posts depends on the type of wood species used and the size of the joist and beam. Joists that cantilever allow for the use of longer joists than those that terminate at the outside face of the beam. It depends on the size of the dimensional lumber you use for your deck support beams and joists. It is critical that you understand building codes before you begin – it will save you time during the permit process. Local building codes will likely offer deck building tables that indicate the allowable deck support post spacing. The spacing also influences the choice of decking with which to finish your project. However, your local building code may influence your design, so understanding what is allowed and what isn’t is your first step to determining deck post spacing. Figure 2. Uncovered Decks and Porches How to Use this Guide Provide two sets of plans, drawn to scale and complete the following (hint: use graph ... posts spaced apart (example: 4 x 4 posts spaced 8’ apart) ... post locations and spacing, joist and beam spans, and any other pertinent information not shown on the section drawing. the span maximum is 9’-1”. Each factor affects the span, the spacing, or both, as well as the placement of beams and support posts that make up the deck frame. at right angles. There are invisible fasteners for securing the boards to the joists, or two 2-1/2” screws or nails through the face into every joist. The dead load is the weight of all the building materials and is commonly calculated at 10psf. Deck support beams are a critical ingredient to making your deck safe for years to come. Pressure-treated or wood preservative doesn’t affect the strength of wood, incising however does. The height of your deck actually can determine how many deck posts you will need. ... build the deck support columns using a poured footing with a concrete tube to just above ground level and use a wood post to continue to deck beam level or you can take the concrete tubes to the height of the deck beams as shown in Figure 2. The joists may rest on two or more beams depending on the span requirements. The shape often determines the direction of the joist grid, which in turn affects the deck board layout and direction. Most codes in North America offer charts that will take into myriad factors that we’ll talk about, plus we’ll go over how to read those charts, as they can be confusing. spacing is half the span plus two. However, cedar will gray with age and requires cleaning and sealing or staining regularly. It’s best to adhere to the Code or involve a Structural Engineer. Finally, it will list various joist lengths, such as 6’, 8’, 10’, and so on. That leaves one beam to be supported by two or more posts. The Titan post anchor is the most advanced hidden wood post anchoring system of its kind. I'm burying 4x4 posts in Concrete as I did with my large fence. The greater the load, the larger the footing dimensions. We’ll assume that one side is attached to your house so that you will need only one support beam because your joists are perpendicular to the house. The IRC reflects proven construction techniques for wood decks using widely accepted conventional construction materials and practices. For instance, if you want to build a deck to fit your circular, above-ground swimming pool, then you are going to need a number of posts to fit the curve of the pool. The span of deck joists depends on the selection of dimensional lumber available in your area. *This stage requires you to be very accurate, so take your time and don’t rush, it … Adding a deck to a home or yard is a great way to create an outdoor living space. The dead and live load the deck will carry helps set the span and spacing of joists and joist dimensions. An accurate deck plan will ensure your permit application is accepted the first time, saving you from having to revise and resubmit. For those in Canada, many consider tables from Ontario and deck support post information found in tables from British Columbia are helpful. … ); the human eye tends to see odd numbers in a more cohesive way than even numbers of fixtures (when visible). For conventional guardrail post installation bolted to the side of the framing, larger framing will provide more strength in the rails. With almost 54,000 businesses, Anne Arundel County is a major hub of commerce and development. Deck Support Column Design . For example, you can space deck support posts for a beam that uses three 2x8s about 7’ apart. Why? Composite decking is commonly 5/4” x 6” and fastens to joists using invisible clips. The spacing depends on the thickness of decking used. The joists need to be spaced 16”o.c. Square or rectangular decks are easier to layout a joist and beam plan for. In most cases, it’s best to start with a full board on the outside edge of the deck and … Building a deck can create an outdoor oasis for entertaining and alfresco meals with family and friends. 5/4 Decking has become the standard for most DIY and professional deck builders. 4 | DECK FRAMING CONNECTION GUIDE F-DECKCODE09 ©2009 SIMPSON STRONG-TIE COMPANY INC. Railing Post-to-Deck Framing (page 15) Lateral Load Connection (page 9) Ledger Attachment (page 8) Stair Tread-to-Stringer (page 16) Joist-to-Ledger The height off the ground, wind-load, snow-load, soil-load capacity, and potential seismic forces also factor into the span. At a minimum, with no ledger board, you’ll need two beams and four deck support posts. Whether the deck framing is free-standing or attached to a structure with a ledger board, joists span the distance and help shape a deck. Eugene has been a DIY enthusiast for most of his life and loves being creative while inspiring creativity in others. BEAM SIZE & ASSEMBLY REQUIREMENTS Deck beam spans shall be in accordance with Table 3 and can extend past the post face up to LB/4 as shown in Figure 3. Shape of the Deck Generally, the maximum joist spacing for boards running perpendicular to the joists is 16”o.c. For example, the table will be called something like “deck beam spans”. Support post spacing depends on where your beam and joists are in relationship to your house. The narrower the spacing between joists, the greater the span can be. It is better to go shorter than to try and maximize span bridging for a more solid and secure platform. HomeAdvisor's DIY Deck Railing & Floor Board Installation Guide provides instructions for laying and staggering decking boards and adding a railing, railing posts, spindles, caps, anchors and bausters to your existing deck. Curved and rounded decks may take a bit more planning but that shouldn’t limit the design options. The wood doesn’t rot or discolor but does need to be cleaned regularly. On the other hand, some rules don’t vary when it comes to deck support posts, such as: Proper deck post spacing follows the deck post spacing chart that is found within your local building code. With post embedded Fig.5 Post setting detail The joists should be spaced at maximum centres according to the table below. Check out the calculator below. Every municipal code is slightly different and you want to base your final calculations on your local code – not an online calculator. If you opt for a two-ply beam, you’ll need at least three deck support posts and deck footings. Position joists to minimize the number of beams your deck will require. The landscaping, or beam to beam, without support the live load requirements t look good if it s. 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